Mew possibilities of quantitative evaluation of body surface potential mapping were studied in 78 patients with ischaemic heart disease. Integral maps of the Q wave, QRS and ST-T intervals were plotted and isochronous maps of ventricular activation time and maps of asynchronous potential minima of the Q wave were determined. Minimum and maximum potential values and their time relations were evaluated in the maps. Left ventricular contraction abnormality detected by left ventricular angiography was determined by a point score and expressed as an index of asynergy. The number of coronary artery branches with significant narrowing was assessed and the extent of coronary artery damage was evaluated by an arbitrary defined index. Using quantitative parameters from the maps, multiple stepwise linear regression was performed. The relationship between map parameters and index of asynergy corresponded to multiple correlation coefficient r=0.69 (p=0.01) in the whole group of patients. In the group of patients with left ventricular contraction abnormality the relationship between these parameters was found to be r=0.87 (p=0.01). The relationship between map parameters and the number of coronary artery branches with significant stenosis was r=0.60 (p=0.01) in the group of patients with positive coronary angiography. In the same group of patients the relationship between map parameters and the index evaluating coronary artery damage was equal to r=0.63 (p=0.01). The data obtained from body surface integral maps enable to quantify cardiac ischaemic damage.